Personalized environmental comfort systems

Traditional HVAC systems primarily condition the entire room air volume to achieve comfortable indoor conditions. In contrast, PECS operate locally, close to the user, improving the immediate microclimate. These systems respond more rapidly than traditional centralized HVAC and, by creating controlled microclimates, reduce the requirements placed on central HVAC, resulting in substantial energy-savings. Current standards for maintaining comfortable indoor conditions insufficiently address PECS. Underlying comfort models predominantly focus on global thermal comfort of the whole body under uniform indoor conditions, offering limited consideration of localized thermal effects. The equivalent temperature model in ISO 14505-2 (2007) is designed exclusively for non-contact areas and is therefore unsuitable for evaluating PECS operating in contact areas, such as seat heating and seat ventilation. The presented equivalent contact temperature model addresses this gap in comfort modeling by explicitly considering heat transfer processes in contact areas. The equivalent contact temperature is calculated to ensure that cumulative heat transfer between skin and contact area is identical in both real and equivalent environment. Complementing the equivalent temperature model, it has been tested under summer conditions with seat ventilation and winter conditions with seat heating. Derived comfort schemes provide a framework for interpreting equivalent contact temperature values. When integrated into a control framework, this model enables a comfort-driven control of PECS, making it a vital foundation for advancing PECS. Local PECS have predominantly been investigated under laboratory conditions, where simplified assumptions limit the transferability of results to real-world scenarios. A field study on a user-controlled PECS, including seat heating, under-desk heating plate, and on-desk heating plate, has demonstrated its acceptance as compensatory solution in cold office environments. The participants accepted the cold thermal conditions and frequently used the system to enhance their individual comfort. At the same time, the findings emphasize the need for additional modules, such as foot heating, to further enhance individual comfort. They also highlight that comfort-driven control should account for individual preferences.